Metered-Dose Inhaler Technique: Mouth vs Nose Inhalation
Patients should always inhale medication from a metered-dose inhaler (MDI) through the mouth, never through the nose. The medication must be delivered directly to the lungs via the oral airway to achieve therapeutic effect.
Proper MDI Mouth Technique
The correct approach involves positioning the MDI mouthpiece between the lips and teeth (closed-mouth technique), or alternatively holding the MDI 2 inches away from an open mouth (open-mouth technique), both of which deliver medication to the lungs 1.
Step-by-Step Inhalation Protocol
The optimal inhalation technique requires:
- Begin with slow, deep inhalation at approximately 30 L/min (taking 3-5 seconds to complete the breath) 1
- Actuate the canister precisely at the start of inhalation, not before or after 1
- Continue inhaling slowly and deeply after actuation—do not stop breathing in when you press the canister 1
- Hold breath for 10 seconds after completing the full inhalation to allow medication deposition in the airways 1
Common Critical Errors to Avoid
The majority of patients (77.5-89.2%) make at least one error when using their MDI, with the most frequent mistakes being failure to exhale to functional residual capacity before actuation and improper timing of canister actuation 2.
Specific pitfalls include:
- Actuating too early (before starting to breathe in) or too late—this is the second most common error, with 121-187 patients actuating the canister prematurely 2
- Inhaling too rapidly rather than maintaining the slow 30 L/min rate 1
- Stopping inhalation at actuation instead of continuing to breathe in deeply 1
- Not holding breath for the full 10 seconds after inhalation 1
When Spacers Are Essential
A spacer or valved holding chamber (VHC) is strongly recommended for:
- All children under 4 years old who cannot coordinate actuation with inhalation 1
- Elderly patients with weak fingers, poor coordination, or cognitive impairment 3, 1
- Any patient who cannot master the coordination between actuation and inhalation 1
- All patients using inhaled corticosteroids to reduce oral thrush risk 1
When using a spacer, actuate only once into the device per inhalation, then immediately begin slow deep inhalation for 3-5 seconds, followed by a 10-second breath hold 1.
Post-Inhalation Care
After using inhaled corticosteroids specifically, rinse the mouth thoroughly and spit to reduce systemic absorption and prevent oral thrush 1.
Why Nasal Inhalation Fails
Inhaling through the nose would deposit medication in the nasal passages and upper airway rather than delivering it to the bronchial tree where bronchodilators and anti-inflammatory medications need to act 4. The entire therapeutic mechanism depends on direct deposition onto the airways, which is only achievable through oral inhalation 4.